Platinum complexes of malonic acid derivatives and process for the preparation thereof

ABSTRACT

Novel platinum complexes wherein malonate derivative is the anion ligand are provided with processes for preparation thereof. The complexes of the present invention have excellent antitumor effect and low toxicity.

SUMMARY OF THE INVENTION

The present invention relates to platinum complexes with excellent antitumor activity represented by the following general formula I and processes for the preparation thereof. ##STR1## wherein A and A' are same or different from each other and selected from the group consisting of ammonia(NH₃), methylamine(CH₃ NH₂), ethylamine(C₂ H₅ NH₂), n-propylamine(n-C₃ H₇ NH₂), isopropylamine(iso-C₃ H₇ NH₂), cyclopropylamine(cyclo-C₃ H₅ NH₂), cyclobutylamine(cyclo-C₄ H₇ NH₂), cyclopentylamine(cyclo-C₅ H₉ NH₂), and cyclohexylamine(cyclo-C₆ H₁₁ NH₂) or optionally, these two amine groups combine together to form a chelating amine such as ethylenediamine(NH₂ CH₂ CH₂ NH₂), trans(±)-1,2-diaminocyclohexane(trans(±)-1,2-(NH₂)₂ -cyclo-C₆ H₁₀), trans(1R,2R)-1,2-diaminocyclohexane(trans(1R,2R)-1,2-(NH₂)₂ -cyclo-C₆ H₁₀), 2,2-dimethyl-1,3-propanediamine(NH₂ CH₂ C(CH₃)₂ CH₂ NH₂), 1,1-cyclobutanedimethaneamine(1,1-cyclo-C₄ H₆ (CH₂ NH₂)₂), 1,1-cyclopentanedimethaneamine(1,1-cyclo-C₅ H₈ (CH₂ NH₂)₂), 1,1-cyclohexanedimethaneamine(1,1-cyclo-C₆ H₁₀ (CH₂ NH₂)₂ ), tetrahydro-4H-pyran-4,4-dimethaneamine(O(CH₂ CH₂)₂ C(CH₂ NH₂)₂), or 1,4-diamino-2-butanol(NH₂ CH₂ CH₂ CH(OH)CH₂ NH₂): R is methyl, ethyl, of propyl or, optionally, these two R groups combine together to form propylene(--CH₂ CH₂ CH₂ --), butylene(--CH₂ (CH₂)₂ CH₂ --), or pentylene(--CH₂ (CH₂)₃ CH₂ --).

It has been found by the present inventors that the platinum complexes containing these anions as provided in the present invention are novel compounds exhibiting excellent antitumor activity which have not known yet.

BACKGROUND OF THE INVENTION

Since the discovery of antitumor activity of cisplatin, i.e., cis-(NH₃)₂ PtCl₂ by B. Rosenberg (Nature, 205,698 (1965)), comprehensive studies including its clinical tests have been performed leading to FDA approval of cisplatin as a chemotherapeutic antitumor agent in 1979. Currently, cisplatin is one of the most widely used antitumor agents and, in particular, is effective for testicular, ovarian, bladder, lung, bone marrow, and larynx cancers, but because of its high toxicity (LD₅₀ =13 mg/kg, M. J. Cleare, Biochimie, 60, 835(1978)), its use is limited. On the other hand, carboplatin, i.e., cis-(NH₃)₂ Pt(CBDCA)(CBDCA=1,1-cyclobutanedicarboxylate) which was approved by FDA in 1989, has much lower toxicity (LD₅₀ =180 mg/kg, M. J. Cleare, Biochimie, 60 (1978)) compared with cisplatin, but its antitumor activity is lower and more expensive than cisplatin. Therefore, a great deal of researches for searching new antitumor agents having a higher antitumor activity and lower toxicity than those of cisplatin or caroplatin is actively underway.

With a view to develop novel platinum antitumor agents having a higher antitumor effect and lower toxicity than those of cisplatin, the present inventors modified the molecular structure of anion and nuetral amine ligand of cisplatin to synthesize new platinum complexes and examined the physiological activity thereof. As a result, the present inventors has found that the platinum complexes bound by a malonic acid derivative containing a double bond at α-position exhibited an excellent antitumor activity and filed an application for the malonic acid derivatives platinum complexes containing sulfur atom as Korean patent application No. 91-11401 filed Jul. 5, 1991 (the corresponding U.S. application has been granted as the U.S. Pat. No. 5,142,075) wherein A═A'═NH₃, CH₃ NH₂, C₂ H₅ NH₂, iso-C₃ H₇ NH₂, cyclo-C₃ H₅ NH₂, AA'═NH₂ CH₂ CH₂ NH₂, 1,2-(NH₂)₂ -cyclo-C₆ H₁₀, CH(OH)(CH₂ NH₂)₂ ; RR═--SCHCHS--, SCH₂ CH₂ S-, R═SCH₃). The present inventors have continued the studies and found that the platinum complexes represented by the formula I containing malonic acids without sulfur of the following general formulas II-A and II-B as anion group have superior antitumor activity to that of carboplatin and cisplatin and much lower toxicity than that of cisplatin. Moreover, the compounds of formula I of the present invention exhibit an improved water-solubility. Thus, it is possible to solve the problems as troubled in the use of cisplatin due to the low water-solubility. ##STR2##

DETAILED DESCRIPTION OF THE INVENTION

The compounds of the present invention as represented by the formula I can be prepared, for example, according to the following procedure.

The esters of dicarboxylic acid of formula II is refluxed in the presence of alkali to obtain alkali metal salts of formula III and then the obtained salts are reacted with barium chloride to form barium salts of formula IV. It is also possible to react esters of dicarboxylic acid with barium hydroxide to directly obtain barium salts of formula IV. ##STR3## wherein R' is ethyl or isopropyl; R is defined as previously as in formula I and; M is ammonium, sodium or potassium.

Then, either of the alkali metal salts of formula III or the barium salts of the formula IV are reacted with an amine-platinum intermediate such as platinum nitrate derivative of formula V or platinum sulfate derivative of formula VI, respectively, to obtain the subject platinum complexes of formula I. ##STR4## wherein A and A' are defined as previously as in formula I.

The platinum nitrate derivatives of formula V or platinum sulfate derivatives of formula VI are prepared by reacting amineplatinum iodides of formula VII with silver nitrate and silver sulfate, respectively, in water solvent for 4 hours as taught by R. C. Harrison (Inorg. Chimica Acta, 46, L15(1980)). ##STR5## wherein A and A' are defined as previously as in formula I.

The amineplatinum iodide VII wherein A and A' are same can be easily obtained by reacting potassium tetrachloro platinate and potassium iodide and corresponding amine compounds according to M. J. Cleare (Biochimie, 60, 835(1978)). Meanwhile, the amineplatinum iodide VII wherein A and A' are different from each other is obtained by reacting the above-obtained amineplatinum iodide wherein A and A' are same with perchloric acid to prepare iodine-bridge bonded dimer, followed by reacting with other kind of amine, according to F. D. Rochon (Can. J. Chem., 64, 1894(1986)).

The detailed description of the process for the preparation of the subject compounds are as herebelow. The anion group, malonic acid derivative of formula II-A and II-B which forms the key structure of the compounds of the formula I is obtained by condensating dialkylketone such as acetone, diethylketone, and dipropylketone, or cyclic ketone such as cyclobutanone, cyclopentanone, and cyclohexanone with malonic acid ethylester or malonic acid isopropylester in the solution of tetrahydrofuran (THF) in the presence of TiCl₄ /CCl₄ catalyst in accordance with W. Lehnert (Tetrahedron 29, 635(1973)). ##STR6## wherein R' is ethyl or isopropyl and n is an integer from 0 to 2.

Dicarboxylic acid esters of formula II as obtained above are hydrolyzed to be reacted with amine-platinum intermediates at aqueous phase. In other words, dicarboxylic acid ester of formula II is stirred in the solvent of ethanol at the room temperature in the presence of 2.0 to 2.2 equivalents of alkali such as KOH or NaOH for 5 to 20 hours to precipitate the aqueous alkali salt of formula Ill. The obtained salt is filtered, washed and then used as such in the synthesis of platinum complex, or it is reacted with equivalent barium chloride to be converted to barium salts of formula IV. Alternatively, dicarboxylic acid esters of formula II is stirred with reflux in aqueous solution for 5-7 hours in the presence of 1.0 to 1.2 equivalents of barium hydroxide(Ba(OH)₂.8H₂ O), then cooled to the room temperature(25° C.) followed by concentration under reduced pressure (3-10 mmHg) with saturated solution, and added by same volume of methanol to directly precipitate the barium salts of formula IV. Depending on the solubility of the final compounds of formula I, alkali salts of formula III or barium salts of formula IV are reacted with amineplatinum nitrate of formula V or amineplatinum sulfate of formula VI in aqueous solution to obtain pure platinum complexes of formula I. For example, if the final platinum complex is slightly soluble in water, the aqueous solution of alkali salt III is mixed with aqueous solution of amineplatinum nitrate V or aqueous solution of amineplatinum sulfate VI and then concentrated to obtain the platinum complex as precipitate while the nitrate or sulfate of alkali is dissolved in water. On the other hand, if the final product is soluble in water, barium salt IV and amineplatinum sulfate VI are reacted in an aqueous solution. As the insoluble barium sulfate is quantitatively precipitated, it can be simply removed. Then, the filtrate is just concentrated, or followed by addition of organic solvent such as acetone or alcohol to obtain platinum complex I in crystalline or powdery form due to its reduced solubility.

The aforementioned procedure for the preparation of the platinum complexes according to the present invention may be summarized as in the following reaction scheme. ##STR7##

The following examples are given by way of illustration and are not to be construed as limiting the invention in any way inasmuch as many variation of the invention are possible within the spirit of the invention.

The elementary analysis of the platinum complexes of the present invention was carried out by using Perkin Elmer C,H,N analyzer. The Infrared Absorption spectrum was measured by Model 101025 FT-IR of MIDAC Co., U.S.A. in the range of 4000-400 cm⁻¹.

EXAMPLE 1 Preparation of (NH₃)₂ Pt(OOC)₂ C═C(CH₃)₂ (A═A'═NH₃ ; R═CH₃ )

To a solution of 5.00 g (25 mmol) malonic acid derivative, (CH₃)₂ C═C(COOC₂ H₅)₂ in 50 ml water, 100 ml of aqueous solution of 9.46 g (30 mmol) of Ba(OH)₂.8H₂ O was added and then refluxed with stirring for 5 hours to hydrolyze. The reactant was cooled to the room temperature (25° C.). After removing the small amount of the precipitate, the filtrate was concentrated under reduced pressure (3 mmHg) to 20 mL. The same volume of methanol was added to stand at low temperature (-5° C.) for 2 hours to obtain white solid precipitate. The obtained precipitate was filtered and washed for two times with methanol and ethylether, respectively, and then dried under reduced pressure (3 mmHg) to obtain 7.25 g (92% yield) of barium salt[(CH₃)₂ C═C(COO)₂ Ba].2H₂ O.

To the solution of 0.95 g (3.00 mmol) of the resulted [(CH₃)₂ C═C(COO)₂ Ba].2H₂ O dissolved in 100 mL of water, gradually added an aqueous solution of (NH₃)₂ PtSO₄ which had been obtained by reacting 1.45 g (3.00 mmol) of amine-platinum intermediate (NH₃)₂ PtI₂ with 0.94 g (3.0 mmol) of Ag₂ SO₄ and stirred for 2 hours. After filtering the precipitate, the filtrate was concentrated under reduced pressure (3 mmHg) to 20 mL to obtain white crystalline powder. The resulted precipitate was filtered, and dried under reduced pressure (3 mmHg) at the room temperature (25° C.) to obtain 0.99 g (89.2% yield) of platinum complex, (NH₃)₂ Pt(OOC)₂ C═C(CH₃)₂ of the following properties:

m.p.: 165° C. (decomp.) Elemental Analysis (%) for (C₆ H₁₂ N₂ O₄)Pt Found: C, 19.2; H, 3.20; N, 7.32 Calcd.: C, 19.4; H, 3.25; N, 7.54 IR bands (KBr;cm⁻¹); 683(m), 797(m), 860(m), 1107(m), 1348(s), 1447(m), 163(s), 3231(s), 3468(m)

EXAMPLE 2 Preparation of ##STR8##

Following the procedure of Example 1 and using the same equivalent of cyclopropylamine instead of ammonia, the platinum complex of ##STR9## was obtained in 72.7% yield.

m.p.: 126° C. (decomp.) Elemental Analysis (%) for (C₁₂ H₂₀ N₂ O₄)Pt(H₂ O) Found: C, 30.9; H, 4.07; N, 5.62 Calcd.: C, 30.7; H, 4.72; N, 5.96 IR bands (KBr;cm⁻¹); 704(m), 812(s), 932(m), 1020(m), 1111(m), 1285(sh), 1437(sh), 1606(s), 1640(s) 2917(m), 3090(s), 3179(s), 3497(m)

EXAMPLE 3 Preparation of (i-C₃ H₇ NH₂)₂ Pt(OOC)₂ C═C(CH₃)₂ (A═A'═i-C₃ H₇ NH₂ ; R═CH₃)

Following the procedure of Example 1 and using the same equivalent of isopropylamine instead of ammonia, the platinum complex of (i-C₃ H₇ NH₂)₂ Pt(OOC)₂ C═C(CH₃)₂ ].H₂ O was obtained in 75.3% yield. m.p.: 119° C. (decomp.) Elemental Analysis (%) for (C₁₂ H₂₄ N₂ O₄)Pt(H₂ O) Found: C, 30.1; H, 5.33; N, 5.86 Calcd.: C, 30.4; H, 5.54; N, 5.92 IR bands (KBr;cm⁻¹); 706(m), 812(m), 935(m), 1115(m), 1273(m), 1368(s), 1588(s), 1644(s), 2973(m), 3084(s), 3196(s), 3420(m)

EXAMPLE 4 Preparation of (NH₂ CH₂ CH₂ NH₂)₂ Pt(OOC)₂ C═C(CH₃)₂ (AA'═NH₂ CH₂ CH₂ NH₂ ; R═CH₃)

Following the procedure of Example 1 and using the same equivalent of ethylenediamine instead of ammonia, the platinum complex of [(NH₂ CH₂ CH₂ NH₂)₂ Pt(OOC)₂ C═C(CH₃)₂ ].H₂ O was obtained in 82.5% yield.

m.p.: 192° C. (decomp.) Elemental Analysis (%) for (C₈ H₁₄ N₂ O₄)Pt(H₂ O) Found: C, 22.8; H, 3.31; N, 6.70 Calcd.: C, 23.1; H, 3.88; N, 6.75 IR bands (KBr;cm⁻¹); 812(m), 1065(m), 1248(m), 1364(s), 1431(m), 1564(s), 1620(s), 1665(s), 3055(s), 3221(s), 3426(m)

EXAMPLE 5 Preparation of ##STR10##

Following the procedure of Example 1 and using the same equivalent of trans(±)-1,2-diaminocyclohexane instead of ammonia, the platinum complex of ##STR11## was obtained in 81.6% yield.

m.p.: 182° C. (decomp.) Elemental Analysis (%) for (C₁₂ H₂₀ N₂ O₄)Pt(H₂ O) Found: C, 31.0; H, 4.27; N, 5.75 Calcd.: C, 30.7; H, 4.72; N, 5.96 IR bands (KBr;cm⁻¹); 706(m), 814(s), 930(m), 1109(m), 1177(m), 1346(s), 1447(sh), 1611(s), 1640(s), 2934(s), 3092(s), 3214(s), 3466(m)

EXAMPLE 6 Preparation of [NH₂ CH₂ C(CH₃)₂ CH₂ NH₂ ]Pt(OOC)₂ C═C(CH₃)₂ (AA'═NH₂ CH₂ C(CH₃)₂ CH₂ NH₂ ; R═CH₃)

Following the procedure of Example 1 and using the same equivalent of 2,2-dimethyl-1,3-diaminopropane instead of ammonia, the platinum complex of {[NH₂ CH₂ C(CH₃)₂ CH₂ NH₂ ]Pt(OOC)₂ C═C(CH₃)₂ }.2H₂ O was obtained in 87.0% yield.

m. p.: 164° C. (decomp.) Elemental Analysis (%) for (C₁₁ H₂₀ N₂ O₄)Pt(2H₂ O) Found: C, 27.7; H, 5.35; N, 5.95 Calcd.: C, 27.8; H, 5.09; N, 5.89 IR bands (KBr;cm⁻¹); 702(m), 810(s), 1034(m), 1113(m), 1175(m), 1387(s), 1443(sh), 1466(s), 1599(s), 2922(m), 3119(s), 3177(s) , 3364(s)

EXAMPLE 7 Preparation of ##STR12##

Following the procedure of Example 1 and using the same equivalent of 1,1-cyclobutanedimethaneamine instead of ammonia, the platinum complex of ##STR13## was obtained in 80.6% yield.

m.p.: 179° C. (decomp.) Elemental Analysis (%) for (C₁₂ H₂₀ N₂ O₄)Pt Found: C, 31.5; H, 4.78; N, 5.80 Calcd.: C, 31.9; H, 4.46; N, 6.21 IR bands (KBr;cm⁻¹); 816(m), 1013(m), 1107(m), 1321(s), 1370(s), 1445(m), 1570(s), 1645(s), 2951(s), 3219(s), 3426(s)

EXAMPLE 8 Preparation of ##STR14##

Following the procedure of Example 1 and using the same equivalent of 1,1-cyclopentanedimethaneamine instead of ammonia, the platinum complex of ##STR15## was obtained in 87.1% yield.

m.p.: 187° C. (decomp.) Elemental Analysis (%) for (C₁₃ H₂₂ N₂ O₄)Pt(H₂ O) Found: C, 36.7; H, 5.06; N, 5.75 Calcd.: C, 36.7; H, 5.39; N, 5.35 IR bands (KBr;cm⁻¹); 812(m), 1017(m), 1111(m), 1350(s), 1445(m), 1607(s), 2872(m), 2947(m), 3069(m), 3216(m), 3287(m), 3443(m)

EXAMPLE 9 Preparation of ##STR16##

Following the procedure of Example 1 and using the same equivalent of 1,1-cyclohexanedimethaneamine instead of ammonia, the platinum complex of ##STR17## was obtained in 83.8% yield.

m.p.: 218° C. (decomp.) Elemental Analysis (%) for (C₁₄ H₂₄ N₂ O₄)Pt(H₂ O) Found: C, 33.8; H, 4.62; N, 6.03 Calcd.: C, 33.8; H, 5.27; N, 5.63 IR bands (KBr;cm⁻¹); 702(m), 818(m), 1103(m), 1227(m), 1345(s), 1368(sh), 1451(m), 1650(s), 2861(m), 2930(m), 3297(m)

EXAMPLE 10 Preparation of [O(CH₂ CH₂)₂ C(CH₂ NH₂)₂ ]Pt(OOC)₂ C═C(CH₃)₂ (AA'═O(CH₂ CH₂)₂ C(CH₂ NH₂)₂ ; R═CH₃)

Following the procedure of Example 1 and using the same equivalent of tetrahydro-4H-pyran-4,4-dimethaneamine instead of ammonia, the platinum complex of [O(CH₂ CH₂)₂ C(CH₂ NH₂)₂ ]Pt(OOC)₂ C═C(CH₃)₂ was obtained in 84.5% yield.

m.p.: 172° C. (decomp.) Elemental Analysis (%) for (C₁₃ H₂₂ N₂ O₅)Pt Found: C, 32.1; H, 4.53; N, 5.72 Calcd.: C, 32.4; H, 4.60; N, 5.82 IR bands (krBr;cm⁻¹); 700(m), 818(m), 1024(m), 1100(m), 1227(m), 1325(s), 1366(sh), 1451(m), 1618(s), 1644(s), 2847(m), 2913(m), 3129(m), 3233(s), 3397(m)

EXAMPLE 11 Preparation of ##STR18##

2.90 g (6 mmol) of (NH₃)₂ PtI₂ was suspended in 150 mL of distilled water and 30 mL of 0.67M aquous perhydrochloric acid solution was added thereto and stirred in boiled water bath at 45° C. for 48 hours. The color of the precipitate was changed from yellow to dark brown. The precipitate was filtered and washed three times with water and dried in vacuo (3 mmHg) in the atmosphere of P₂ O₅ to obtain 1.96 g (70% yield) of iodine-bridge bonded dimer [Pt(NH₃)I₂ ]₂. 1.86 g (2 mmol) of [Pt(NH₃)I₂ ]₂ was suspended in 50 mL of distilled water which had been deairated. Then, 0.6 mL (6 mmol) of cyclopenthylamine ##STR19## was added and stirred at the room temperature (25° C.) for 12 hours to produce 1.65 g (75% yield) of yellow mixed amine-platinum intermediate ##STR20## 1.653 g (3.0 mmol) of the resulted yellow mixed amine-platinum intermediate ##STR21## and 0.935 g (3.0 mmol) of Ag₂ SO₄ were reacted as described in Example 1 to obtain aqueous solution of ##STR22## and this solution was gradually added to the 100 mL solution in which 0.95 g (3.0 mmol) of [(CH₃)₂ C═C(COO)₂ Ba].2H₂ O was dissolved and stirred for 2 hours. After filtering off the white precipitate, the filtrate was dried under reduced pressure (3 mmHg) and recrystallized in 10 mL of methanol to obtain yellow platinum complex ##STR23## with 87.2% yield.

m.p.: 154° C. (decomp.) Elemental Analysis (%) for (C₁₁ H₂₀ N₂ O₄)Pt(3H₂ O) Found: C, 26.4; H, 3.98; N, 5.60 Calcd.: C, 26.8; H, 5.31; N, 5.68 IR bands (KBr;cm⁻¹); 810(m), 1111(m), 1362(s), 1443(m), 1603(s), 2870(m), 2953(m), 3100(s), 3216(s), 3462(m)

EXAMPLE 12 Preparation of ##STR24##

Following the procedure of Example 11 and using the same equivalent of cyclohexylamine instead of cyclopenthylamine, the platinum complex of ##STR25## was obtained in 72.6% yield.

m.p.: 142° C. (decomp.) Elemental Analysis (%) for (C₁₂ H₂₂ N₂ O₄)Pt(2H₂ O) Found: C, 29.5; H, 4.94; N, 5.46 Calcd.: C, 29.5; H, 5.35; N, 5.72 IR bands (KBr;cm⁻¹); 814(m), 1109(m), 1372(s), 1445(m), 1607(s), 1640(s), 2859(m), 2928(s), 3113(m), 3218(m)

EXAMPLE 13 Preparation of ##STR26##

Following the procedure of Example 11 and using the same equivalent of isopropylamine instead of ammonia, the platinum complex of ##STR27## was obtained in 64.5 yield.

m.p.: 164° C. (decomp.) Elemental Analysis (%) for (C₁₄ H₂₆ N₂ O₄)Pt(4H₂ O) Found: C, 29.5; H, 4.12; N, 5.99 Calcd.: C, 30.4; H, 6.19; N, 5.06 IR bands (KBr;cm⁻¹); 808(m), 1022(m), 1229(m), 1254(m), 1368(s), 1620(s), 2928(s), 3108(s), 3198(s), 3439(m)

EXAMPLE 14 Preparation of ##STR28##

Following the procedure of Example 11 and using the same equivalent of isopropylamine and cyclohexylamine instead of ammonia and cyclopenthylamine respectively, the platinum complex of ##STR29## was obtained in 70.1% yield.

m.p.: 146° C. (decomp.) Elemental Analysis (%) for (C₁₅ H₂₈ N₂ O₄)Pt(5H₂ O) Found: C, 30.0; H, 4.72; N, 5.84 Calcd.: C, 30.7; H, 6.54; N, 4.78 IR bands (KBr;cm⁻¹); 737(m), 777(m), 1113(m), 1364(s), 1402(sh), 1555(s), 1642(m), 2930(m), 3235(m), 3395(m)

EXAMPLE 15 Preparation of (NH₃)₂ Pt(OOC)₂ C═C(C₂ H₅)₂ (A═A'═NH₃ ; R═C₂ H₅)

Following the procedure of Example 1 and using (C₂ H₅)₂ C═C(COOC₂ H₅)₂ instead of a malonic acid derivative, (CH₃)₂ C═C(CCOC₂ H₅)₂, the platinum complex of [(NH₃)₂ Pt(OOC)₂ C═C(C₂ H₅)₂ ].2H₂ O was obtained in 71.9% yield.

m.p.: 159° C. (decomp.) Elemental Analysis (%) for (C₈ H₁₆ N₂ O₄)Pt(2H₂ O) Found: C, 22.5; H, 4.15; N, 6.16 Calcd.: C, 22.1; H, 4.63; N, 6.43 IR bands (KBr;cm⁻¹); 698(m), 808(m), 885(m), 1125(m), 1258(sh), 1370(s), 1462(sh), 1609(s), 2969(m), 3102(s), 3237(s)

EXAMPLE 16 Preparation of ##STR30##

Following the procedure of Example 15 and using the same equivalent of cyclopropylamine instead of ammonia, the platinum complex of ##STR31## was obtained in 76.2% yield.

m.p.: 128° C. (decomp.) Elemental Analysis (%) for (C₁₄ H₂₄ N₂ O₄)Pt(2H₂ O) Found: C. 32.1; H, 4.72; N, 5.41 Calcd.: C, 32.6; H, 5.47; N, 5.43 IR bands (KBr;cm⁻¹); 810(m), 1022(m), 1123(m), 1258(sh), 1372(s), 1460(sh), 1624(s), 2971(m), 3098(s), 3204(s), 3445(m)

EXAMPLE 17 Preparation of ##STR32##

Following the procedure of Example 15 and using the same equivalent of trans(±)-1,2-diaminocyclohexane instead of ammonia, the platinum complex of ##STR33## was obtained in 79.0% yield.

m.p.: 178° C. (decomp.) Elemental Analysis (%) for (C₁₄ H₂₄ N₂ O₄)Pt(2H₂ O) Found: C, 32.6; H, 5.28; N, 5.31 Calcd.: C, 32.6; H, 5.47; N, 5.43 bands (KBr;cm⁻¹); 708(m), 812(m), 1177(m), 1256(sh), 1350(s), 1454(sh), 1636(s), 2942(s), 3094(s), 3206(s)

EXAMPLE 18 Preparation of ##STR34##

Following the procedure of Example 1 and using ##STR35## instead of a malonic acid derivative, (CH₃)₂ C═C(COOC₂ H₅)₂, the platinum complex of ##STR36## was obtained in 71.3% yield.

m.p.: 159° C. (decomp.) Elemental Analysis (%) for (C₇ H₁₂ N₂ O₄)Pt(5H₂ O) Found: C, 17.7; H, 3.30; N, 7.41 Calcd.: C, 17.8; H, 4.68; N, 5.91 IR bands (KBr;cm⁻¹); 743(m), 829(m), 963(m), 1298(m), 1356(s), 1387(s), 1618(s), 1661(s), 3100(s), 3264(s), 3324(s), 3488(s)

EXAMPLE 19 Preparation of ##STR37##

Following the procedure of Example 18 and using the same equivalent of cyclopropylamine instead of ammonia, the platinum complex of ##STR38## was obtained in 72.7% yield.

m.p.: 154° C. (decomp.) Elemental Analysis (%) for (C₁₃ H₂₀ N₂ O₄)Pt(4H₂ O) Found: C, 28.7; H, 4;64; N, 5.86 Calcd.: C, 29.2; H, 5.27; N, 5.23 IR bands (KBr;cm⁻¹); 745(m), 826(m), 934(m), 1022(m), 1385(s), 1622(s), 3108(s), 3202(s), 3424(m)

EXAMPLE 20 Preparation of ##STR39##

Following the procedure of Example 18 and using the same equivalent of trans(±)-1,2-diaminocyclohexane instead of ammonia, the platinum complex of ##STR40## was obtained in 76.4% yield.

m.p.: 183° C. (decomp.) Elemental Analysis (%) for (C₁₃ H₂₀ N₂ O₅)Pt(4H₂ O) Found: C, 28.8; H, 4.71; N, 5.87 Calcd.: C, 29.2; H, 5.27; N, 5.23 IR bands (KBr;cm⁻¹); 745(m), 808(m), 961 (m), 1067(m), 1179(m), 1372(s), 1404(s), 1617(s), 1661(s), 2861(m), 2938(m), 3096(s), 3187(s), 3449(m)

EXAMPLE 21 Preparation of ##STR41##

Following the procedure of Example 1 and using ##STR42## instead of a malonic acid derivative, (CH₃)₂ C═C(COOC₂ H₅)₂, the platinum complex of ##STR43## was obtained in 63.2% yield.

m.p.: 182° C. (decomp.) Elemental Analysis (%) for (C₈ H₁₄ N₂ O₄)Pt(3H₂ O) Found: C, 21.1; H, 3.60; N, 6.69 Calcd.: C, 21.3; H, 4.46; N, 6.21 IR bands (KBr;cm⁻¹); 754(m), 812(m), 905(m), 1051 (re), 1350(s), 1426(sh), 1559(s), 2959(m), 3237(s), 3459(m)

EXAMPLE 22 Preparation of ##STR44##

Following the procedure of Example 21 and using the same equivalent of cyclopropylamine instead of ammonia, the platinum complex of ##STR45## was obtained in 61.6% yield.

m.p.: 112° C. (decomp.) Elemental Analysis (%) for (C₁₄ H₂₂ N₂ O₄)Pt(2H₂ O) Found: C, 32.7; H, 5.30; N, 5.49 Calcd.: C, 32.8; H, 5.10; N, 5.46 IR bands (KBr;cm⁻¹); 748(m), 828(m), 1024(m), 1123(m), 1213(m), 1339(s), 1383(m), 1615(s), 2962(m), 3388(s), 3447(m)

EXAMPLE 23 Preparation of ##STR46##

Following the procedure of Example 1 and using ##STR47## instead of a malonic acid derivative, (CH₃)₂ C═C(COOC₂ H₅)₂, the platinum complex of ##STR48## was obtained in 82.1% yield.

m.p.: 145° C. (decomp.) Elemental Analysis (%) for (C₉ H₁₆ N₂ O₄)Pt(5H₂ O) Found: C, 21.6; H, 3.57; N, 6.73 Calcd.: C, 22.4; H, 5.00; N, 5.80 IR bands (KBr;cm⁻¹); 696(m), 789(m), 924(m), 1113(m), 1372(s), 1601(s), 2851(m), 2940(m), 3088(s), 3167(s), 3273(s), 3470(m)

EXAMPLE 24 Preparation of ##STR49##

Following the procedure of Example 23 and using the same equivalent cyclopropylamine instead of ammonia, the platinum complex of ##STR50## was obtained in 72.3% yield.

m.p.: 136° C. (decomp.) Elemental Analysis (%) for (C₁₅ H₂₄ N₂ O₄)Pt(2H₂ O) Found: C, 34.6; H, 4.81; N, 5.58 Calcd.: C, 34.2; H, 5.35; N, 5.31 IR bands (KBr;cm⁻¹); 646(m), 826(m), 1022(m), 1252(m), 1375(s), 1397(s), 1634(s), 2932(m), 3090(s), 3202(s)

EXAMPLE 25 Preparation of ##STR51##

Following the procedure of Example 23 and using the same equivalent of isopropylamine instead of ammonia, the platinum complex of ##STR52## was obtained in 82.6% yield.

m.p.: 167° C. (decomp.) Elemental Analysis (%) for (C₁₅ H₂₈ N₂ O₄)Pt(2H₂ O) Found: C, 34.1; H, 5.94; N, 5.14 Calcd.: C, 33.9; H, 6.07; N, 5.27 IR bands (KBr;cm⁻¹); 791(m), 808(m), 1117(m), 1254(m), 1385(s), 1576(s), 1634(s), 2930(m), 2971(m), 3129(m) 3189(m), 3466(m)

EXAMPLE 26 Preparation of ##STR53##

Following the procedure of Example 23 and using the same equivalent of trans(±)-1,2-diaminocyclohexane instead of ammonia, the platinum complex of ##STR54## was obtained in 74.9% yield.

m.p.: 189° C. (decomp.) Elemental Analysis (%) for (C₁₅ H₂₄ N₂ O₄)Pt(2H₂ O) Found: C, 34.2; H, 5.13; N, 5.37 Calcd.: C, 34.2; H, 5.35; N, 5.31 IR bands (KBr;cm⁻¹); 791(m), 806(m), 1065(m), 1227(m), 1250(m), 1360(s), 1445(m), 1622(s), 2855(m), 2924(s) 3111(m), 3216(m), 3439(m)

EXAMPLE 27 Preparation of ##STR55##

Following the procedure of Example 23 and using the same equivalent of 1,1-cyclobutanedimethaneamine instead of ammonia, the platinum complex of ##STR56## was obtained in 83.8% yield.

m.p.: 201° C. (decomp.) Elemental Analysis (%) for (C₁₅ H₂₄ N₂ O₄)Pt Found: C, 36.9; H, 4.86; N, 6.12 Calcd.: C, 36.7; H, 4.92; N, 5.70 IR bands (KBr;cm⁻¹); 787(m), 810(m), 1003(m), 1227(m), 1252(m), 1314(m), 1362(s), 1445(m), 1638(s), 2857(m) 2926(m), 3127(m), 3233(m), 3401(m)

EXAMPLE 28 Preparation of ##STR57##

Following the procedure of Example 23 and using the same equivalent of 1,1-cyclopentanedimethaneamine instead of ammonia, the platinum complex of ##STR58## was obtained in 90.1% yield.

m.p.: 192° C. (decomp.) Elemental Analysis (%) for (C₁₆ H₂₆ N₂ O₄)Pt(H₂ O) Found: C, 36.7; H, 5.06; N, 5.75 Calcd.: C, 36.7; H, 5.39; N, 5.35 IR bands (KBr;cm⁻¹); 810(m), 1019(m), 1221(m), 1252(m), 1327(m), 1360(s), 1447(m), 1644(s), 2868(m) 2936(s), 3117(m), 3221(s)

EXAMPLE 29 Preparation of ##STR59##

Following the procedure of Example 23 and using the same equivalent of 1,1-cyclohexanedimethaneamine instead of ammonia, the platinum complex of ##STR60## was obtained in 89.3% yield.

m.p.: 198° C. (decomp.) Elemental Analysis (%) for (C₁₇ H₂₈ N₂ O₄)Pt(H₂ O) Found: C, 38.5; H, 5.50; N, 5.57 Calcd.: C, 38.0; H, 5.62; N, 5.21 IR bands (KBr;cm⁻¹); 694(m), 810(m), 920(m), 1036(m), 1225(m), 1352(s), 1454(m), 1636(s), 2851(m), 2924(s) 3127(m), 3218(m)

EXAMPLE 30 Preparation of ##STR61##

Following the procedure of Example 23 and using the same equivalent of tetrahydro-4H-pyran-4,4-dimethaneamine instead of ammonia, the platinum complex of ##STR62## was obtained in 85.6% yield.

m.p.: 168° C. (decomp.) Elemental Analysis (%) for (C₁₆ H₂₆ N₂ O₅)Pt(2H₂ O) Found: C, 34.9; H, 5.26; N, 5.08 Calcd.: C, 34.5; H, 5.42; N, 5.02 IR bands (KBr;cm⁻¹); 808(m), 1026(m), 1100(m), 1229(m), 1250(sh), 1366(s), 1603(s), 1630(s), 2853(m), 2926(s) 3110(s), 3189(s), 3443(s)

EXAMPLE 31 Preparation of ##STR63##

Following the procedure of Example 12 and using the same equivalent of CH₂ (CH₂)₄ C═C(COOC₂ H₅)₂ instead of a malonic acid derivative, (CH₃)₂ C═C(COOC₂ H₅)₂, the platinum complex of ##STR64## was obtained in 71.5% yield.

m.p.: 180° C. (decomp.) Elemental Analysis (%) for (C₁₅ H₂₆ N₂ O₄)Pt(2H₂ O) Found: C, 34.3; H, 6.19; N, 5.17 Calcd.: C, 34.0; H, 5.71; N, 5.29 IR bands (KBr;cm⁻¹); 810(m), 1229(m), 1254(m), 1346(s), 1366(s), 1449(m), 1603(s), 2853(m), 2926(s), 3221(s) 3464(m )

IN VIVO TEST AGAINST LEUKEMIA L1210 CELL LINE

The platinum complexes of the present invention were evaluated for antitumor activity against murine Leukemia L1210 cell line, according to the standard method of Goldin et al. (Europ. J. Cancer. 17, 129 (1981)). Each test group consisted of 8 BDF₁ mice of 6 to 8 weeks old. 10⁶ cells of Leukemia L1210 were implanted by intraperitoneal injection to each mouce, and the platinum test compounds dissolved in 0.9% physiological saline solution were administered intraperitoneally on days 1, 5 and 9 at various doses in the range of 10-40 mg/Kg. Table 1 presents the result of the observation on Increased Life Span (%) and number of survived animals on day 60. From Table 1, it is clearly shown that the antitumor activity of the platinum complexes of the present invention is superior to that of cisplatin or carboplatin.

                  TABLE 1                                                          ______________________________________                                         Antitumor Activity Against Murine L1210 Leukemia                                        Dose                 Number of Survived                               Compound of                                                                             (mg/kg)  Increased Life                                                                             Animals on day 60                                ______________________________________                                         Example 5                                                                               40       76.6        0                                                         10       44.1        0                                                Example 12                                                                              40       >233.3      8/8                                                       10       >130.0      3/8                                              Example 18                                                                              40       128                                                                   10       39                                                           Example 19                                                                              10       >278.4      7/8                                              Example 22                                                                              30       >241.8      5/8                                              Example 24                                                                              40       >261.1      5/8                                                       10       88.4        0                                                Cisplatin                                                                                4       84.5        0                                                          1       38.6        0                                                Carboplatin                                                                             40       59.3        0                                                         20       46.9        0                                                ______________________________________                                     

What is claimed is:
 1. A platinum complex represented by the following formula I: ##STR65## wherein R is methyl or ethyl, or these two R groups combine to form propylene, butylene, or pentylene; A and A' are same or different from each other and are selected from the group consisting of ammonia, methylamine, isopropylamine, cyclopropylamine, cyclobutylamine, and cyclohexylamine in the case of being monodentate neutral ligand, or A and A' combine to form chelating amine such as ethylenediamine, trans(±)-1,2-diaminocyclohexane, 2,2-dimethyl-1,3-propanediamine, 1,1-cyclobutanedimethaneamine, 1,1-cyclopentanedimethaneamine, 1,1-cyclohexanedimethaneamine, or tetrahydro-4H-pyran-4,4-dimethaneamine. 